PROJECT ABSTRACT (SCALE UP COMPONENT) Depression is the leading mental health cause of the Global Burden of Disease and accounts for 37% of the mental health related Disability Adjusted Life Years (DALYs) in India. However, despite the knowledge of evidence-based clinical treatments and delivery models, treatment gaps exceed 90% in rural areas. In order to address this science to service gap, our aim is to generate knowledge on the most effective and cost-effective approaches to sustainably scale up the ESSENCE `package' (collaborative stepped care delivery of two evidence-based clinical treatments for moderate to severe depression in primary care attenders) to four districts (population of approximately 5.3 million) in the state of Madhya Pradesh with delivery entirely carried out by existing health workers funded by the government. ESSENCE consists of two complementary, sequential randomized control trials, conducted over five years to address following specific aims: a) the development and evaluation of the effectiveness and cost- effectiveness of On-Line Training (OLT) interventions (with and without guidance) compared with Face- to-Face (F2F) training on the competence of Accredited Social Health Activists (ASHA workers), community health workers deployed in India's National Health Mission, to deliver the Healthy Activity Program (HAP), an evidence-based brief psychological treatment for depression in primary care attenders; and b) the development and evaluation of the effectiveness and cost-effectiveness of two levels of implementation support interventions to address the key barriers to the collaborative stepped care delivery of evidence-based clinical treatments for depression (the HAP and antidepressant medication) compared with the current strategy of training alone, on outcomes in patients with moderate to severe depression in primary care. ESSENCE builds on a substantial body of evidence in the study country, led by the program PIs, to capitalize on the unique and timely opportunity offered by the strong engagement of our research program with the Ministry of Health, Government of Madhya Pradesh to address the critical knowledge gaps regarding the training and implementation support strategies necessary to scale-up evidence-based treatments for depression in a low resource setting. The most innovative aspect of research is the use of technology platforms for delivery of both the training and implementation support interventions to enhance the likelihood of future scaling up of these interventions. The knowledge gained will be the first from any low or middle income country for such training and implementation interventions and could thus be instrumental in influencing the mental health policy agenda beyond the study country.